001/**
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements.  See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License.  You may obtain a copy of the License at
008 *
009 *      http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017package org.apache.camel.component.vm;
018
019import java.util.HashMap;
020import java.util.Map;
021import java.util.concurrent.BlockingQueue;
022import java.util.concurrent.atomic.AtomicInteger;
023
024import org.apache.camel.Endpoint;
025import org.apache.camel.component.seda.QueueReference;
026import org.apache.camel.component.seda.SedaComponent;
027import org.apache.camel.component.seda.SedaEndpoint;
028
029/**
030 * An implementation of the <a href="http://camel.apache.org/vm.html">VM components</a>
031 * for asynchronous SEDA exchanges on a {@link BlockingQueue} within the classloader tree containing
032 * the camel-core.jar. i.e. to handle communicating across CamelContext instances and possibly across
033 * web application contexts, providing that camel-core.jar is on the system classpath.
034 *
035 * @version 
036 */
037public class VmComponent extends SedaComponent {
038    protected static final Map<String, QueueReference> QUEUES = new HashMap<String, QueueReference>();
039    protected static final Map<String, SedaEndpoint> ENDPOINTS = new HashMap<String, SedaEndpoint>();
040    private static final AtomicInteger START_COUNTER = new AtomicInteger();
041
042    @Override
043    public Map<String, QueueReference> getQueues() {
044        return QUEUES;
045    }
046    
047    @Override
048    public QueueReference getQueueReference(String key) {
049        return QUEUES.get(key);
050    }
051
052    @Override
053    protected void doStart() throws Exception {
054        super.doStart();
055        START_COUNTER.incrementAndGet();
056    }
057
058    @Override
059    protected void doStop() throws Exception {
060        if (START_COUNTER.decrementAndGet() <= 0) {
061            // clear queues when no more vm components in use
062            getQueues().clear();
063            // also clear endpoints
064            ENDPOINTS.clear();
065        }
066    }
067
068    @Override
069    protected Endpoint createEndpoint(String uri, String remaining, Map<String, Object> parameters) throws Exception {
070        if (ENDPOINTS.containsKey(uri)) {
071            return ENDPOINTS.get(uri);
072        }
073
074        SedaEndpoint answer = (SedaEndpoint) super.createEndpoint(uri, remaining, parameters);
075
076        ENDPOINTS.put(uri, answer);
077        return answer;
078    }
079}